Optimized multicast messaging in LPWA networks

ABSTRACT

Various embodiments comprise systems, methods, architectures, mechanisms and apparatus for optimizing the delivery of multicast messages to a set of targeted (receiver) devices via a low power wide area (LPWA) network such as by minimizing a number of gateway devices in a set of gateway devices needed to reach the target devices, by optimizing the use of radio communication resources to minimize costs associated with using metered backhaul network services (e.g., costs associated with using cellular network backhaul services), by maximizing the resiliency, speed, or synchronization of the set of gateway devices, by favoring operator-owned resources, or by achieving other goals consistent with operator policies, preferences and other considerations.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to wireless communicationssystems and related networks, and more particularly to multicast routingof communications to target end devices via a plurality of gateways in alow power network.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart, which may be related to various aspects of the present inventionthat are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Given the enormous and growing number of Internet of Things (IoT)devices to be serviced, and the expected insufficiency of traditional(licensed band) network services, various stakeholders in the fastgrowing IoT ecosystem are turning to low power wide area (LPWA) networksusing unlicensed spectrum as an IoT servicing solution. For example,members of the LoRa Alliance are promoting the LoRaWAN protocol forapplications such as IoT LPWAN connectivity via unlicensed bands, thoughthe use of licensed bands is technically also feasible. See, e.g., LoRaAlliance TS001-1.0.4 LoRaWAN® L2 1.0.4 Specification (2020). Otherprotocols, standards, and the like directed to LPWA networks are beingpromoted by other groups.

LoRaWAN and similar networks are typically laid out in a star-of-starstopology in which gateways (e.g., gateways, concentrators, routers,access points, base stations, etc.) relay transmissions betweenend-devices and a central Network Server at the backend. Gateways areconnected to a Network Server via standard IP connections, whereasend-devices use single-hop radio-frequency (RF) communication to one ormany gateways. All communication is generally bi-directional, althoughuplink communication from an end-device to a Network Server is expectedto be the predominant traffic.

LoRa and other LPWA networks offer support for multicast messages so asto reach many receiving IoT devices simultaneously for performing commonor group tasks, such as distributing software updates and definingcontrol and/or application functions for a cluster devices performing acertain function and/or located in a given region (e.g., street lightsin a given city, controlled holiday lighting, a certain type ofcontrollers in a factory).

Unfortunately, the relatively high latency of low power wide areanetworks becomes problematic when there is a need to reach these devicesin a substantially simultaneous manner, such as for simultaneousactivation of community lighting, triggering of sensors, and/or otherapplications.

SUMMARY

Various deficiencies in the prior art are addressed by systems, methods,architectures, mechanisms and apparatus for optimizing the delivery ofmulticast messages to a set of targeted (receiver) devices via a lowpower wide area (LPWA) network such as by minimizing a number of gatewaydevices in a set of gateway devices needed to reach the target devices,by optimizing the use of radio communication resources to minimize costsassociated with using metered backhaul network services (e.g., costsassociated with using cellular network backhaul services), by maximizingthe resiliency, speed, or synchronization of the set of gateway devices,by favoring operator-owned resources, or by achieving other goalsconsistent with operator policies, preferences and other considerations.

In accordance with one embodiment, a method for routing a multicastmessage from a network server toward a plurality of target devicesconfigured to communicate with a low power wide area (LPWA) networkcomprising a plurality of gateways, the method comprising: determining,for a multicast message to be routed toward the target devices via theLPWA network, a plurality of multicast paths wherein each multicast pathcomprises a respective set of gateways configured to reach all targetdevices; determining, for each respective set of gateways forming amulticast path, a composite weighted metric (CWM) in accordance with aplurality of selection factors comprising, for each gateway, a number oftarget devices reachable only through the gateway, a received signalstrength indicator (RSSI) of target devices proximate the gateway, and abackhaul message delivery cost of the gateway, wherein each selectionfactor is weighted in accordance with an operator policy; selecting amulticast path comprising a set of gateways P having a lowest CWM; andtransmitting the multicast message toward only the gateways included inthe selected set of gateways P.

Additional objects, advantages, and novel features of the invention willbe set forth in part in the description which follows, and will becomeapparent to those skilled in the art upon examination of the followingor may be learned by practice of the invention. The objects andadvantages of the invention may be realized and attained by means of theinstrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the presentinvention and, together with a general description of the inventiongiven above, and the detailed description of the embodiments givenbelow, serve to explain the principles of the present invention.

FIG. 1 depicts a block diagram of a system using a low power wide area(LPWA) network useful in illustrating the various embodiments.

FIG. 2 depicts an exemplary signaling diagram and method according to anembodiment; and

FIG. 3 depicts a flow diagram of a method for least cost routing ofmulticast messages in a low power, wide area network.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the sequence of operations as disclosedherein, including, for example, specific dimensions, orientations,locations, and shapes of various illustrated components, will bedetermined in part by the particular intended application and useenvironment. Certain features of the illustrated embodiments have beenenlarged or distorted relative to others to facilitate visualization andclear understanding. In particular, thin features may be thickened, forexample, for clarity or illustration.

DETAILED DESCRIPTION

The following description and drawings merely illustrate the principlesof the invention. It will thus be appreciated that those skilled in theart will be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of theinvention and are included within its scope. Furthermore, all examplesrecited herein are principally intended expressly to be only forpedagogical purposes to aid the reader in understanding the principlesof the invention and the concepts contributed by the inventor(s) tofurthering the art, and are to be construed as being without limitationto such specifically recited examples and conditions. Additionally, theterm, “or,” as used herein, refers to a non-exclusive or, unlessotherwise indicated (e.g., “or else” or “or in the alternative”). Also,the various embodiments described herein are not necessarily mutuallyexclusive, as some embodiments can be combined with one or more otherembodiments to form new embodiments.

The numerous innovative teachings of the present application will bedescribed with particular reference to the presently preferred exemplaryembodiments. However, it should be understood that this class ofembodiments provides only a few examples of the many advantageous usesof the innovative teachings herein. In general, statements made in thespecification of the present application do not necessarily limit any ofthe various claimed inventions. Moreover, some statements may apply tosome inventive features but not to others. Those skilled in the art andinformed by the teachings herein will realize that the invention is alsoapplicable to various other technical areas or embodiments.

Various embodiments provide systems, apparatus, and methods configuredto determine, for members of a multicast/broadcast address in a LoRaWANnetwork, an optimized selection of gateway devices so as to optimizemulticast message delivery to a set targeted devices in a manner thatminimizes the number of gateways used to reach the targeted devices,optimizes usage of radio resources, and minimizes backhaul costs.

FIG. 1 depicts a block diagram of a system using a low power wide area(LPWA) network useful in illustrating the various embodiments.Specifically, the system 100 of FIG. 1 comprises a plurality of enddevices 110 comprising Internet of Things (IoT) or similar types ofsensors, controls and the like (illustratively water meters 110-1, airquality meters 110-2, traffic controllers 110-3, lighting controllers110-4 and/or other controller/sensors) configured to receive messagesfrom one or more gateways 120 within a low power wide area (LPWA)network, such as a LPWA network in accordance with LoRaWAN or similarprotocols.

As depicted in FIG. 1, the LPWA network is simplistically depicted ascomprising four gateway devices; namely, 120-1 through 120-4 (gateways120). A typical LPWA network may comprise thousands or even millions ofsuch gateways. It is noted that the gateways forming an LPWA network aretypically arranged in a star of stars type of configuration as is known.

As depicted in FIG. 1, a network server 130 is configured to coordinatewith application servers 140 (illustratively three application servers140-1, 140-2, and 140-3) to support the communications between theapplication servers 140 and end devices 110 such as for the delivery toend devices 110 of application control messages, application data,application software updates, end device configuration information andso on as provided by the application servers 140. Further, the networkserver 130 is configured to receive various messages including sensordata, end device status information and so on via the gateway devices120 forming the LPWA network, and to transmit such received messages tothe appropriate application server 140.

As depicted in FIG. 1, various network management functions/entities areshown such as a network operations and management (O&M) platform 150, anoperator policy server 160, a network monitoring and analysis platform170, and platforms/servers/entities supporting other managementfunctions 180. For purposes of this discussion, the network monitoringand analysis platform 170 may be used to gather and analyze networkstatistics such as associated with the LPWA, the various gateways 120forming the LPWA, the network server 130, and optionally the applicationservers 140.

Various elements or portions thereof depicted in FIG. 1 and havingfunctions described herein are implemented at least in part as computingdevices having communications capabilities, including for example thesensors/controllers 110, gateways 120, network server 130, applicationservers 140, O&M platform 150, an operator policy server 160, a networkmonitoring and analysis platform 170, and platforms/servers/entitiessupporting other management functions 180. These elements or portionsthereof may comprise computing devices of various types, thoughgenerally including a processor element (e.g., a central processing unit(CPU) or other suitable processor(s)), a memory (e.g., random accessmemory (RAM), read only memory (ROM), and the like), variouscommunications and input/output interfaces (e.g., enablingcommunications with other entities as indicated in FIG. 1), and so on aswill be appreciated by those skilled in the art and informed by theteachings herein. Further, the various network managementfunctions/entities may be implemented as fewer entities (e.g., combiningO&M platform 150 and operator policy server 160), and may be implementedin whole or in part vie remote or third party platforms.

As such, the various functions depicted and described herein may beimplemented at the elements or portions thereof as hardware or acombination of software and hardware, such as by using a general purposecomputer, one or more application specific integrated circuits (ASIC),or any other hardware equivalents or combinations thereof. In variousembodiments, computer instructions associated with a function of anelement or portion thereof are loaded into a respective memory andexecuted by a respective processor to implement the respective functionsas discussed herein. Thus, various functions, elements and/or modulesdescribed herein, or portions thereof, may be implemented as a computerprogram product wherein computer instructions, when processed by acomputing device, adapt the operation of the computing device such thatthe methods or techniques described herein are invoked or otherwiseprovided. Instructions for invoking the inventive methods may be storedin tangible and non-transitory computer readable medium such as fixed orremovable media or memory, or stored within a memory within a computingdevice operating according to the instructions.

Multicast Messages to Target End Devices

Within the context of transmitting a message from an application server142 to a target group of end devices 110, various embodimentscontemplate using a multicast message such as where the target group ofend devices may comprise a set of end devices sharing a common multicastMAC address. Further, the target group of end devices may be configuredto remain in a power saving or quiescent mode of operation (i.e., unableto receive and/or respond to communications from a gateway 120) until aspecific “activation time” whereupon each of the target group of enddevices exit the power saving mode of operation and tunes/selects theappropriate RF channel(s) associated with the multicast MAC address soas to receive therefrom messages, control information and the like.Further, sensor devices associated with the target group of end devicesmay also transmit sensor information back toward the network server 130or application server 140 via one or gateways 120 within reach of orcapable of communicating with the end device.

Given the enormous scale of a typical LPWA network, various embodimentsautomatically select for each multicast message at least one set ofgateways 120 providing a least cost (or at least lower cost) routing ofmulticast messages, which selection enables improved load balancingwithin the gateways 120 forming the LPWA network, helps to guide messagerouting so as to avoid congestion at final or intermediate gatewaysalong a MAC address path or tree, and/or achieve other networkmanagement goals such as described herein.

It is noted that multiple sets of gateways (e.g., three lowest costsets, or three lowest cost sets where each set uses a different one ofseveral identified necessary but critically loaded/congested gateways)may be utilized to support redundancy, failover, resiliency, and/orother criteria.

In the example of FIG. 1, the network server 130 is operably connectedto each of the gateways 120 and application servers 140, as indicated byrespective solid lines therebetween. However, for a given multicast treefor services from a first application server 140-1, it is determinedthat only two of the gateways (e.g., 120-1 and 120-2) are needed toreach all of the relevant gateways, as indicated by a dashed lineextending from the first application server 140-1 though the networkserver 130 and to the first and second gateways 120-1 and 120-2. Asnoted herein, more or fewer gateways may be used to support suchmulticast trees depending upon application requirements (e.g., monetarycost, security, redundancy, and so on).

FIG. 2 depicts an exemplary signaling diagram and method according to anembodiment.

At step 201, upload messages from the various end devices reach thenetwork server 130 via one or more gateways 120, whereupon the networkserver 130 gathers the various metrics associated with these uploadmessages such as a received signal strength indicator (RSSI) or otherinformation indicative of received signal strength at the transmittingend device, routing information indicative of specific gateways used toroute the message (useful in identifying over utilized and/orunexpectedly inactive gateways), and other metrics/information suitablefor use in monitoring the performance of the LPWA network, the backbonenetwork, and other elements supporting the upload messages.

At step 202, the network server 130 processes received upload messagesand forwards the received upload messages and variousmetrics/information to the appropriate application servers 140.

At step 203, the operations and management (O&M) platform 150 gathersloading and other information/metrics pertaining to the gateways 120forming the LPWA network. In various embodiments suchinformation/metrics are retrieved via the network server 130. In otherembodiments, such information/metrics may be retrieved by the networkserver 130 and/or various entities within the backbone networksupporting the LPWA network. Specifically, FIG. 2 depicts communicationsbetween the network server 130 and O&M platform 150, and between thenetwork server 130 and the various gateways 120, such communicationsbeing used to request desired information/metrics, receive automaticallyor schedule delivery of such information/metrics and so on.

At step 204, the O&M platform 150 and operator policy server 160 provideinformation useful in assessing gateway costs and multicast routing;namely, operator policies, identification of information/metrics ofinterest, waiting to be applied to the identified information/metrics ofinterest, and other information useful in ascertaining gateway androuting costs.

At step 205, for a multicast message intended to be simultaneouslyprovided to each of a plurality of targeted end devices, an optimumcomposite weighted metric (CWM) value is determined to identify at leastone set of p gateways to reach all of targeted end devices associatedwith a multicast message. A method for determining this one or set of pgateways will be discussed in more detail below with respect to FIG. 3.In various embodiments this determination is depicted as being made atthe network server 130. However, in various other embodiments thisdetermination may be made at another network management entity.

At step 206, the multicast message is transmitted toward those gatewayswithin the set of p gateways determined that step 205.

It is noted that multiple or redundant or nested multicast messagerouting trees may be used to provide message resiliency such as in thecase of mission-critical type control messages. As such, in someembodiments at step 2052 or more sets of gateways or determined, whereeach of the two or more sets of gateways may comprise lowest/lower costgateway sets, a lowest cost gateway set and a backup high-reliabilitygateway set, or any other gateway set having different criteria.

Generally speaking, when the network server 130 needs to send a payloadto set of targeted devices, it determines an optimized set of gatewaysto deliver the payload as multicast messages. This determination isbased on a composite metric constructing using various factors ofinterest (e.g., performance, gateway cost, operator preferences and thelike as described herein), where the various factors of interest areassigned weights such that each potential gateway to be included withinthe optimized set of gateways may be associated with a respective cost.The set of gateways meeting and optimal criteria such as an optimal costcriteria, and optimal resiliency criteria, and optimal speed criteriaand the like may be selected as a single set of gateways fortransmission of the multicast message, or one of several sets ofgateways for transmission of the multicast message.

FIG. 3 depicts a flow diagram of a method for least cost routing ofmulticast messages in a LoRaWAN or similar type of network. The methodmay be performed at any provider equipment (PE) management entity suchas the O&M platform 150, operator policy server 160, network monitoringand analysis platform 170, other network management entity, networkserver 130, or other device operably configured to obtain and processthe relevant data as discussed below. This determining device maycomprise, illustratively, a network manager operably configured tocommunicate with an EPC core, WiFi access network, and/or other networkcapable of supporting or implementing the system 100 of FIG. 1.

For purposes of this discussion, it will be assumed that multicastmessages are configured to be transmitted to respective target groups ofend devices via a network of gateways (e.g., a LoRaWAN network orsimilar) such as described above with respect to FIG. 1, and that themethod operates to determine for each multicast message a respectiveleast or lower cost set of gateways to receive the multicast messagesuch that the respective target group of end devices substantiallysimultaneously receives the message.

At step 310, the end devices capable of communicating with each gateway(i.e., reachable by each gateway) are identified. Referring to box 315,such end devices may comprise those actively communicating with thegateway, those recently communicating with the gateway, those proximatethe gateway such that they should be able to communicate with thegateway when activated, those fenced by the gateway or other proximatedevices which should be able to communicate with the gateway whenactivated, and/or other end devices. It is noted that step 310 may beperformed independent of the method 300 described herein, such as wherea gateway device is constantly identifying reachable end devices. Invarious embodiments the gateways periodically report reachable devicesto a management entity. With a star-of-stars topology LPWA network, thepackets from a given device are carried by multiple Gateways to theserver. This, in addition providing data transport, provides the serverwith information about the reachability of each of the devices throughthe multitude of the gateways in the network. This reachabilityinformation may be used in the various embodiments while sending packetstoward the devices, such as for optimizing the number of gateways and/orthe cost associated with using these gateways.

At step 320, for each multicast message a determination is made as tothe corresponding target group of end devices to which the multicastmessage should be transmitted toward. For example, a target group of enddevices may comprise a group of lighting or HVAC control devicesassociated with a building or industrial complex to which a multicastmessage including message or command configured to cause a coordinatedillumination, HVAC operation, software update, status check, and/orother operation by each of the end devices within the target group ofend devices. The target group of end devices may comprise a set of enddevices sharing a common multicast MAC address that are configured tobecome active at a specific time (i.e., exit a power saving mode ofoperation) and tune/select the appropriate RF channel associated withthe multicast MAC address so as to receive therefrom messages, controlinformation and the like.

At step 330, for each multicast message a determination is made as tothe corresponding group of gateways capable of communicating with atleast one end device within the target group end devices determined atstep 320. That is, at step 330 the gateways within the network capableof communicating with any of the target group end devices are identifiedor determined.

At step 340, a respective cost is associated with each member of amulticast message gateway group using a plurality of weighted costfactors. Referring to box 345, the cost factors F and correspondingweighting W may be based upon some or all of a number of target devicesreachable through a particular gateway, whether a particular targetdevices reachable through multiple gateways, RSSI values and/or otherchannel strength/utilization indicators provided via target deviceuplink messages and the like, backhaul message delivery costs, gatewayusage radiofrequency (RF) costs, gateway usage unavailability cost(e.g., assigned lost opportunity cost), gateway messaging load cost,operator policies and/or preferences, application type, applicationpriority, reliability requirements, sensitivity (e.g., secrecy level,confidential level) of multicast payload, size of multicast payload,and/or other factors and/or weights as appropriate to the use case. Thatis, given the various cost factors deemed to be relevant and waited inaccordance with the use case, application, urgency of implementation,operator requirement, customer requirement and the like, a cost ofrouting a multicast message via each of the relevant gateways isdetermined.

At step 350, for each multicast message a selection is made of a set ofgateways capable of communicating with the target group of end devicesat a lowest cost (or other performance goal such as speed, resiliency,synchronization, application-specific performance characteristics, andthe like) as determined using a composite weighted metric (CWM). Thatis, given that a number of different sub groupings or subsets of therelevant gateways may be used to deliver in multicast message to thetarget end devices, the sub grouping or subsets of gateways providing aleast cost routing of the multicast message is selected or use. It isnoted that multiple sets of gateways may be utilized to supportredundancy, failover, resiliency, and/or other criteria.

In various embodiments, for each multicast session an optimized set (orsets) of gateways numbered p among all reachable gateways is determinedin accordance with the following equation, where Fi is a value of afactor i, Wi is a weight given to a factor i, GWk is a favorability/costmetric of a gateway k, and p is a subset of gateways among all reachablegateways which can be used to reach all target end devices:

$\sum\limits_{k = 1}^{k = p}{\sum\limits_{i = 1}^{i = n}{GWk*\left( {{Fi} \times {Wi}} \right)}}$

The various factors Fi and their given weight may be determined based onindividual sessions, session types, application types, session orapplication priority, operator performance requirements and/or othergoals. Weighting may comprise assigning unitary fractions to each of thei factors Fi to be considered (i.e., adding up each of the correspondingweights Wi equals 1). Other methods of weighting may also be used.

Multicast sessions having cost-related goals may prioritize propagationof instructions to end devices 110 via the (monetarily) least cost pathavailable. For sessions or applications where cost is the primary goal,an operator may be willing to use third party gateways 120 only if suchuse is absolutely necessary to reach the relevant population of enddevices 110. Typically, an operator will favor the use of the operator'sown gateways 120, and may favor the use of specific high-performancegateways deployed by the operator to support high volume, lower costmulti-cast sessions/streams (e.g., high volume gateways deployed atstadiums or other events to support transient high-volume access to databy attendees).

Multicast sessions having higher performance goals may prioritize rapidor simultaneous propagation of instructions to end devices 110, whereingateways 120 offering faster, more reliable, or more synchronizedoperation are weighted higher than other gateways 120. For sessions orapplications where performance is critical, an operator may over-weightcorresponding factors such as the use of paths formed with gateways 120associated with third parties even if additional costs are incurred.

Multicast sessions having higher reliability or redundancy goals mayprioritize propagation of instructions to end devices 110 via at leasttwo paths, such as where end devices 110 and/or gateways 120 operate inchallenging/difficult environments. For sessions or applications wherereliability/redundancy is critical, an operator may be willing to usemultiple paths sufficient to provide communication with every relevantend device 110 via at least two proximate gateways 120 (e.g., two pathsmays be used to deliver the instructions, or two multicast sessions maybe used to deliver the instructions where each session uses arespective/different path).

Some exemplary factors Fi are presented below with respect to Table 1.

TABLE 1 Weight Wi Weight Weight Wi (lowest Wi (most Factor Fi cost)(fastest) reliable) Number of relevant target devices 0.02 0.04 0.06reachable through a gateway Number of relevant target devices 0.02 0.040.06 reachable only through a gateway RSSI values and/or other channel0.02 0.04 0.06 strength/utilization indicators of a gateway provided viatarget device uplink messages Backhaul message delivery costs of 0.020.04 0.06 a gateway Radiofrequency (RF) usage costs of 0.02 0.04 0.06 agateway Gateway messaging load cost 0.02 0.04 0.06 Gateway current 0.020.04 0.06 utilization/congestion level Gateway predicted 0.02 0.04 0.06utilization/congestion level based on size/duration of multicast payloadGateway usage unavailability cost 0.02 0.04 0.06 (e.g., assigned lostopportunity cost) Gateway suitability to application 0.02 0.04 0.06 typeGateway suitability to application 0.02 0.04 0.06 priority Gatewaysuitability to reliability 0.02 0.04 0.06 requirements Gatewaysuitability to performance 0.02 0.04 0.06 requirements Gatewaysuitability to sensitivity of 0.02 0.04 0.06 multicast payload Gatewayconformance with 0.02 0.04 0.06 operator policies and/or preferences(speed, reliability, captive or third party, etc.) Other factors 0.020.04 0.06

The above is an example of weightages assigned to different factorsunder consideration, it does not preclude or limit inclusion of otherfactors or variation of the assigned weights. These weightages may beinfluenced further from operational data analytics and historicaloperational, observed degree of compliance with intended policies andspecifications.

Various modifications may be made to the systems, methods, apparatus,mechanisms, techniques and portions thereof described herein withrespect to the various figures, such modifications being contemplated asbeing within the scope of the invention. For example, while a specificorder of steps or arrangement of functional elements is presented in thevarious embodiments described herein, various other orders/arrangementsof steps or functional elements may be utilized within the context ofthe various embodiments. Further, while modifications to embodiments maybe discussed individually, various embodiments may use multiplemodifications contemporaneously or in sequence, compound modificationsand the like. It will be appreciated that the term “or” as used hereinrefers to a non-exclusive “or,” unless otherwise indicated (e.g., use of“or else” or “or in the alternative”).

Although various embodiments which incorporate the teachings of thepresent invention have been shown and described in detail herein, thoseskilled in the art can readily devise many other varied embodiments thatstill incorporate these teachings. Thus, while the foregoing is directedto various embodiments of the present invention, other and furtherembodiments of the invention may be devised without departing from thebasic scope thereof.

What is claimed is:
 1. A method for routing a multicast message from a network server toward a plurality of target devices configured to communicate with a low power wide area (LPWA) network comprising a plurality of gateways, the method comprising: determining, for a multicast message to be routed toward the target devices via the LPWA network, a plurality of multicast paths wherein each multicast path comprises a respective set of gateways configured to reach all target devices; determining, for each respective set of gateways forming a multicast path, a composite weighted metric (CWM) in accordance with a plurality of selection factors comprising, for each gateway, a number of target devices reachable only through the gateway, a received signal strength indicator (RSSI) of target devices proximate the gateway, and a backhaul message delivery cost of the gateway, wherein each selection factor is weighted in accordance with an operator policy; selecting a multicast path comprising a set of gateways P having a lowest CWM; and transmitting the multicast message toward only the gateways included in the selected set of gateways P.
 2. The method of claim 1, wherein the RSSI of target devices proximate the gateway comprises a measured RSSI values received in uplink message from target devices.
 3. The method of claim 1, wherein the RSSI of target devices proximate the gateway comprise calculated RSSI values based on proximity of gateway and target devices.
 4. The method of claim 1, wherein the plurality of selection factors for each gateway further comprises at least one of a number of target devices reachable by the gateway, a gateway radio frequency (RF) usage cost, and a gateway messaging load cost.
 5. The method of claim 4, wherein the plurality of selection factors for each gateway further comprises at least one of a current gateway utilization level cost, and a predicted gateway utilization level.
 6. The method of claim 1, wherein the plurality of selection factors for each gateway further comprises at least one of a gateway application type suitability, a gateway application priority suitability, a gateway reliability suitability, a gateway security suitability, and a gateway performance suitability.
 7. The method of claim 1, wherein the plurality of selection factors for each gateway further comprise at least one a gateway usage unavailability cost, and a gateway conformance with operator policies/preferences.
 8. The method of claim 1, further comprising: selecting a second multicast path comprising a set of gateways P2 having a second lowest CWM; and said transmitting comprises transmitting the multicast message toward the gateways included in each of the two selected sets of gateways P and P2.
 9. The method of claim 1, wherein for each multicast session a selected set of gateways numbered among all reachable gateways is determined in accordance with the following equation, where Fi is a value of a factor i, Wi is a weight given to a factor i, GWk is a favorability/cost metric of a gateway k, and p is a subset of gateways among all reachable gateways which can be used to reach all target end devices: $\sum\limits_{k = 1}^{k = p}{\sum\limits_{i = 1}^{i = n}{GWk*{\left( {{Fi} \times {Wi}} \right).}}}$
 10. The method of claim 9, wherein the weight Wi given to each factor Fi is selected to provide a CWM for determining a set of gateways P configured to provide a low cost multicast tree.
 11. The method of claim 9, wherein the weight Wi given to each factor Fi is selected to provide a CWM for determining a set of gateways P configured to provide a high speed multicast tree.
 12. The method of claim 9, wherein the weight Wi given to each factor Fi is selected to provide a CWM for determining a set of gateways P configured to provide a high reliability multicast tree.
 13. The method of claim 9, further comprising: selecting a second multicast path comprising a set of gateways P2 having a second lowest CWM; and said transmitting comprises transmitting the multicast message toward the gateways included in each of the two selected sets of gateways P and P2.
 14. The method of claim 13, wherein the weight Wi given to each factor Fi is selected to provide a CWM for determining sets of gateways P and P2 configured to provide low cost multicast trees.
 15. The method of claim 13, wherein the weight Wi given to each factor Fi is selected to provide a CWM for determining sets of gateways P and P2 configured to provide high reliability multicast trees.
 16. The method of claim 13, wherein the weight Wi given to each factor Fi is selected to provide a CWM for determining a set of gateways P configured to provide a high reliability multicast tree, and a CWM for determining a set of second gateways P2 configured to provide a high reliability multicast tree.
 17. A system for determining multicast routes for messages from a network server toward a plurality of target devices configured to communicate with a low power wide area (LPWA) network comprising a plurality of gateways, the system comprising: a network manager, operably coupled to the network server and configured for: determining, for a multicast message to be routed toward the target devices via the LPWA network, a plurality of multicast paths wherein each multicast path comprises a respective set of gateways configured to reach all target devices; determining, for each respective set of gateways forming a multicast path, a composite weighted metric (CWM) in accordance with a plurality of selection factors comprising, for each gateway, a number of target devices reachable only through the gateway, a received signal strength indicator (RSSI) of target devices proximate the gateway, and a backhaul message delivery cost of the gateway, wherein each selection factor is weighted in accordance with an operator policy; selecting a multicast path comprising a set of gateways P having a lowest CWM; and transmitting the multicast message toward only the gateways included in the selected set of gateways P.
 18. The system of claim 17, wherein the RSSI of target devices proximate the gateway comprises a measured RSSI values received in uplink message from target devices.
 19. The system of claim 17, wherein the RSSI of target devices proximate the gateway comprise calculated RSSI values based on proximity of gateway and target devices.
 20. The system of claim 17, wherein the plurality of selection factors for each gateway further comprises at least one of a number of target devices reachable by the gateway, a gateway radio frequency (RF) usage cost, and a gateway messaging load cost.
 21. The system of claim 17, wherein for each multicast session a selected set of gateways numbered among all reachable gateways is determined in accordance with the following equation, where Fi is a value of a factor i, Wi is a weight given to a factor i, GWk is a favorability/cost metric of a gateway k, and p is a subset of gateways among all reachable gateways which can be used to reach all target end devices: $\sum\limits_{k = 1}^{k = p}{\sum\limits_{i = 1}^{i = n}{GWk*{\left( {{Fi} \times {Wi}} \right).}}}$
 22. A tangible and non-transient computer readable storage medium storing instructions which, when executed by a computer, adapt the operation of the computer to provide a method for routing multicast messages from a network server toward a plurality of target devices configured to communicate with a low power wide area (LPWA) network comprising a plurality of gateways, the method comprising: determining, for a multicast message to be routed toward the target devices via the LPWA network, a plurality of multicast paths wherein each multicast path comprises a respective set of gateways configured to reach all target devices; determining, for each respective set of gateways forming a multicast path, a composite weighted metric (CWM) in accordance with a plurality of selection factors comprising, for each gateway, a number of target devices reachable only through the gateway, a received signal strength indicator (RSSI) of target devices proximate the gateway, and a backhaul message delivery cost of the gateway, wherein each selection factor is weighted in accordance with an operator policy; selecting a multicast path comprising a set of gateways P having a lowest CWM; and transmitting the multicast message toward only the gateways included in the selected set of gateways P. 